Is it correct?: Mostly. Willa Cather wrote it; however, it doesn’t appear in My Antonia, which that Riffle post might suggest.

Source: The Song of the Lark, 1932 Edition. It’s from the preface, and that muse.jhu.edu site is the closest I can get you online.

Full quotation: “The chief fault of [The Song of the Lark] is that it describes a descending curve; the life of a successful artist in the full tide of achievement is not so interesting as the life of a talented young girl ‘‘ﬁghting her way,’’ as we say. Success is never so interesting as struggle—not even to the successful, not even to the most mercenary forms of ambition.